diff --git a/src/engine/objects/Mob.java b/src/engine/objects/Mob.java
index 40105e64..da895a12 100644
--- a/src/engine/objects/Mob.java
+++ b/src/engine/objects/Mob.java
@@ -807,7 +807,8 @@ public class Mob extends AbstractIntelligenceAgent {
         // only if this building has a blueprint.
         // otherwise use the mob cache location.
 
-        if (this.building != null && building.getBlueprintUUID() != 0) {
+        if (this.building != null && building.getBlueprintUUID() != 0
+            && this.building.getHirelings().contains(this) == false) {
 
             int maxSlots = 10;
 
diff --git a/src/engine/objects/NPC.java b/src/engine/objects/NPC.java
index e026cd25..b69f2bea 100644
--- a/src/engine/objects/NPC.java
+++ b/src/engine/objects/NPC.java
@@ -352,9 +352,12 @@ public class NPC extends AbstractCharacter {
 			this.stamina.set(this.staminaMax);
 		}
 
-		//add this npc to building
+		// Add this npc to building hireling list if not there yet.
+		// For some reason the mob is initialized twice when
+		// createMobWithNoID() is called.
 
-		if (this.building != null) {
+		if (this.building != null &&
+		    this.building.getHirelings().contains(this) == false) {
 
 			int maxSlots = 10;